Optimisation of thermo mechanical treatments using cryogenic rolling and aging of the high strength aluminium alloy AlZn5.5MgCu (AA7075). Optimierung der thermomechanischen Behandlung am Beispiel der hochfesten Aluminiumlegierung AlZn5,5MgCu mittels Tieftemperaturwalzen

In this study, we consider the optimisation of mechanical properties and the microstructure of the high strength and difficult‐to‐work aluminium alloy AA7075 by cryogenic rolling. In order to reduce the grain size into the (ultra)fine‐grained regime, cryogenic rolling is used to introduce different amount of plastic strain. We discuss how rolling at lower temperatures allows the introduction of higher strains on the one hand, and suppresses dynamic recovery and aging effectively on the other hand. Our results demonstrate that, in combination with an appropriate post‐processing aging treatment, an outstanding combination of strength and ductility can be achieved.